Calcipotriol hydrate was described in Acta Crystallographica. Section C, Crystal Structure Communication, Col. C49, No. 3, 1993: 618-612, and in WO 94/15912 (ES 2111287) presents a procedure for obtaining the product from organic solvents and water. This method entails several difficulties:                the organic solvents used must be removed afterwards, a disadvantage from an environmental point of view and contrary to “clean chemistry” practices;        usable product yield is lost in the transformation, because part of it is left behind in the solvents or slurry;        as with the majority of crystallized products in the presence of organic solvents, the end product usually contains residual organic solvents, a very important aspect, which is regulated in relation to the active pharmaceutical components.        